Arc-lamp electrode.



C. A. B. HALVORSON, JR.

ARG LAMP BLEGTRODE.

APPLIGATION FILED MARA, 1911.

Patented Mar. 25, 1913 Hls flt'borneg.

, UNITED sfrnrnws PATENT cerros.'

CROMWELL A; B. HALVORSON, JR., 0F LYNN, MASSACHUSETTS, ASSIGNOR T0 ELECTRIC CMPA'NY, A C ORCPOBLATON 0F lfE'iv YQRK.

Anc-LAMP E Lnc'rnonn.

Specification of Letters Patent.

Patented Mai". 25, 1913.

Application led March 4, 1911. Serial No. 612,379.

To all whom t may concern: g

Be it known that I, CnoMwELL A. B. HMV

vonsoN, Jr., a citizen of the United States,

aluminous arc in which a liouiidfpool isI formed upon the arcing end of the electrode.

It has hitherto been proposed to use anelectrode -of this character composed of a mixture of magnetite, 'rutile and chroinite, this mixture being inclosed in an iron shell to `be used as the negative electrode,V and to use as the positive electrode a very slowly consuming electrode and which -is known in about the arcing face.

' higher current than the art asa non-consuming electrode.'v an arc is much longer than the arc vformed between carbon electrodes, and in practice commonly has a length of about-,an inch. When the arc is burning between electrodes of this character, a pool is formed o n'the negativel electrode which moves irregularly Under certain conditions, however, and particularly when it is required that the negative electrode should have a smaller diameter than Ausual with an abnormally high titanium content,l

and should at the same time be run at a ordinarily employed, the tip of the electrode, particularly during the -irst portion of its life, becomes 'very hot, the liquid pool becomes very much enlarged and extends in fact over thefentire arcing endof the electrode, and, as the iron shell, as .ordinarily used, is consumed rather rapidly, the molten material exhibits a tendency tol flow over the edge of the electrode and present a rounded surface to the arc. The cathode blast issues from the negative `electrode in a direction normal to the surface4 of the electrode at that point, and, whenthe are is burning near the edgel of the electrode, the arc is bowed outwardly to an excessive extent and is liable to he frequently ruptured. In the type of lamp in which electrodes of this character are ordinarily used, theelectrodes may or may not be in engagement when the' lamp is not in operation, and, whenI they are separated 'or brought together and separated to strike the arc, the arc is liable to be bowed outn "Such wardly to such an extent as to beruptured altogether. The electrodes are then again brought together and the process repeated, producing what is known in 'the art` as jumping. tered in the use of a negative electrode having a rounded'end, in' that the arc is not struck with as great certaintybetween such an electrode and the non-consuming elec-` trode as between a-nelectrode presenting a flat surface and a corresponding `nonconsuming` electrode. tendency of the negative electrode to burn with a rounded end by providing die electrode with a second metallic shell; prefen ably of iron. l

In 'the ligure, 1 indicates' the outer shell within which the inner shell 2 is sprung'and vfrictionally held. The-innershelLZ is filled with the usual electrode composition 3,' such as magnetite mixture. The tip of the electrode is closed by a seal 4. g fi' .My understanding of the" reason for the second shell curing the defect hitherto noted is that the outer shell is kept much cooler than the inner shell, or than the 'ordinary single shell.- 'The contact between the two shells in my electrode is imperfect .at best,

with the consequencethat the heat of the inner shell is but irnperfectlyv transmitted to the outer shell." lhe outer ,shell being coolerthan the inner diie is more' slowly con` sumed than the inner fone, or than the ordi- A further diticultyis encoun-` ly have overcome this nary single shell witll the conse uence that e (l the moltenmaterial is caused to assume ,a flattened condition andburn withI a flatsurface. Whatever may :be the correct theory, however, vfor the second shell curing vthe defect hitherto noteddl have found in practice that it docs overcome this defect' and .have found by experiment that a single shell having the samI thickness as that of the combined thickness ofthe two shells does notaccomplisln the same result.I ,I- am not limited to the hse of two4 concentric shells, since, in some cases, three or more such shellsmay be used. y f lVhileI l have. described my inventionas particularly applicable to. anelectrode in l which the arc producing material is a` mix.

ture of magnet-ite, rutile and chromite, it is obvious that it is-applicable to any electrode producing a luminous arc and in which the electrode material is fusible and the end ,becomes rounded in'operation. Furthermore,

f iron, it is obvious that other metals could while` vhave described a shell as made of be. used. It is also obvious that, While I have mentioned a non-consuming electrode las the anode, my 4invention does not depend material giving a'luminous( arc and'aplurality of concentric metallic shells in frictional Contact with each other`- l2. An arc light electrode having a coreA giving a luminous are and two concentric iron shells 1n frlctlonal contact.

3. An arc light electrode having a core composed of a luminous-arc material inclosed in a metallic shell which is surroundedlby a second lmetallic shell in frictional contact with -the iirst.

4. An -arc light electrode having a core containing fusible luminous arc material surrounded by a plurality of metallic shells in frictional contact with each other.

5. An arc light electrode composed of material producing a luminous arc and which forms a liquid pool during operation, 'provided With a plurality of metallic shells `in frictional contact with each other, whereby aid fusible material burns with a Hat surace.

6. An arc light electrode composed of a material yielding 'a luminous arc springing from a molten pool, provided with two me` tallic shells and a thermal insulating layer between the two shells.

7. An arc light electrode composed of a material yielding a luminous arc'springing from a molten pool, inclosed within a lnetallic shell, said shell being surrounded by a second shell concentric therewith, and means for thermally insulating said second shell from'said iirst shell.

In witness whereof, I have hereunto set my hand this second dayof March', 1911.

CROMWELL A. 1i. HlLvoaSoN, Jn.

lVitnesses JOHN A. McMANUs, Jr.,

CHARLES A. BARNARD.

(iopies o! this patent may be obtained for ve cents each, by addressing the Commissioner of Patents,

Washington, D. .0.4 e 

